1. Field of Invention
The technical scope of the invention is that of vehicle tracks and more particularly that of endless tracks and the linking means between the chain links of an endless track. It is known to produce vehicle tracks by assembling different links using pins and connectors.
2. Description of the Related Art
Reference may be made, for example, to patents U.S. Pat. No. 4,700,992 and U.S. Pat. No. 4,139,241 that describe such tracks.
By way of example, FIGS. 1a and 1b show such a type of known linking means. FIG. 1a shows four links 1 (1a, 1b) assembled together and FIG. 1b shows an exploded view of different components of this assembly. The parts shown in black in the Figures are made of rubber.
We can see in these Figures that the links 1 are not directly linked to one another. They are made integral by means of pins 2 and connectors 3.
Thus, each link 1 incorporates two parallel drill holes 4 that each receives a pin 2 (only one pin is shown in FIG. 1b).
We can see in FIG. 1b that each pin 2 thus carries two links 1a, 1b that are symmetrical to one another. Each pair of links 1 is then fixed to another similar pair by means of connectors 3 that are attached to the pin 2. FIG. 1a shows such an assembly.
We note in FIG. 1a that, after the chain links 1 have been assembled with the pins 2, the ends 2a of the pins 2 protrude from the external edges of the chain links 1 thereby enabling the connectors 3 to be fixed. Each pair of links 1a, 1b is thus fixed to a neighboring pair by two end connectors 3.
We further note that each pair of chain links 1a, 1b is also fixed to the next pair by a central connector 5 (also visible in FIG. 1b). This central connector incorporates two flanges fixed by screws and carries an extension 5a that acts as a guiding tooth for the track.
Classically, the end connectors 3 comprise two cylindrical holes 3a, 3b intended to cap the pins 2, and linked by tongues 6a, 6b. A screw 7 passes through the tongues 6a, 6b cooperating with a female thread arranged in one of the tongues. Tightening this screw allows the tongues 6a, 6b to be elastically brought together thereby causing the connector 3 to tighten on the pins 2.
The connector 3 and the ends of the pin may be provided with one of several flat areas (not shown). Such an arrangement will ensure the relative positioning of the links giving a prior bending between successive links. The winding of the tracks on the sprocket wheel, the idler and the end rollers of the running gear.
As may be seen more particularly in FIG. 1b, each pin 2 incorporates two rings 8 of a coating of synthetic material. The pin thus incorporates three supports 9a, 9b and 9c (that may be cylindrical or prismatic), such supports delimiting the two rings 8. The connectors 3 and 5 are fixed to these supports.
More often than not the rings 8 are made of rubber, either in a single block by duplicate molding or by threading different concentric rings bonded to one another (rings called “adherites”).
These rings 8 are positioned between the pin 2 and the link 1. They enable part of the mechanical stresses received by the links to be absorbed. They also enable a metal on metal friction to be avoided between the pin 2 and the link when the track is in operation. In fact, such friction would lead to the premature wear of the pins thereby causing failures.
Furthermore, the rubber of which the rings 8 are made allows different deformations for the pins 2 from one link to another during the operation of the track. The rings 8 must not slip during operation and through their deformation they withstand the relative torsions of the pins 2 with respect to the links 1.
Such a classical assembly, however, suffers from drawbacks.
Indeed, the deformations to which they are subjected cause substantial heating of the rings 8. These are further heated by the links 1 themselves which, when traveling, are stressed by being crushed between the ground and the vehicle's rollers. The rings 8, overheated, have difficulty cooling down, since rubber-type materials do not conduct heat well.
This results in a deterioration of the rings, which end up by no longer separating the pins 2 from the links 1. This leads, in the more or less long term, to a metal on metal contact of the pin 2 with the links 1 (1a, 1b). This contact increases the overheating thereby destroying the adherite rings as well as other rubber parts in the link. Resistance to the forward motion of the vehicle is thus increased and can lead to the failure of the tracks.